Thermosetting resin composition for build-up

ABSTRACT

Provided are a thermosetting resin composition for build-up method which gives a cured product excellent in heat resistance, an insulating material for build-up method using thereof and a build-up print circuit board. The thermosetting resin composition for build-up method comprises (A) an epoxy resin represented by formula (I), (B) a curing agent for epoxy resin and (C) a poly(ether sulfone), an insulating material for build-up method and a build-up print circuit board using thereof.                    
     in the formula, Gly represents glycidyl group: R represents each independently, an alkyl group having 1 to 10 carbons, and the like; i represents each independently a numeral of 0 to 4; when i is 2 or more, R may be the same or different from each other; and n represents a repeating number of 1 to 10.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermosetting resin composition forbuild-up method. More precisely, it relates to a thermosetting resincomposition for build-up method comprising an epoxy resin, a curingagent for epoxy resin and poly(ether sulfone). In addition, it relatesto an insulating material for build-up method and a build-up printcircuit board using said thermosetting resin composition.

2. Description of the Related Art

In recent years, a high-density mounting has been demanded as theprogress of downsizing, light weighing and thin shaping of electronicapparatuses. By this reason, it has become required in print circuitboard not only to minimize circuit patterns but also to reduce diameterof through holes and via holes, and to adopt blind via holes. Increasingattention has been given to build-up print circuit boards obtainable bythe build-up method as a product meeting with these requirements.Practical insulating materials for build-up circuit board include aphoto-sensitive resin type having merit that a number of via holes, canbe formed in one operation by exposure-development step and athermosetting resin type which allows formation of finer via holes, byusing the laser process. In case of photo-sensitive resin typeinsulating material, there Is a limitation in selection of thephoto-sensitive resin which gives a photosensitivity to the resincomposition thereof, and there are many know-hows in theexposure-development step. Thus, at present, the thermosetting resintype insulating material is attracting more attention.

Proposed thermosetting resin compositions for use in the thermosettingresin type insulating materials include, in addition to a compositioncomprising a thermosetting resin alone such as an epoxy resin, a phenoxyresin or the like, a composition comprising a thermosetting resin and athermoplastic resin. For example, JP-A-7-33991 and JP-A-7-34048 describea thermosetting resin containing an epoxy resin and a poly(ethersulfone).

When the conventional thermosetting resin composition is used, however,it has been difficult to obtain an insulating material for build-upmethod which is satisfactory in heat resistance.

The object of the present invention is to provide a thermosetting resincomposition for build-up method which gives a cured product excellent inheat resistance, to provide an insulating material for build-up methodusing said thermosetting resin composition and to provide a build-upprint circuit board using said insulating material.

SUMMARY OF THE INVENTION

As the result of extensive studies for solving above described problems,the inventors have found that the above object can be attained by usinga composition comprising a specific epoxy resin, a curing agent forepoxy resin and a poly(ether sulfone), thus the present invention hasbeen completed.

That is, the present invention relates to (I) a thermosetting resincomposition for build-up method comprising (A) an epoxy resinrepresented by the formula (1) , (B) a curing agent for epoxy resin, and(C) a poly(ether sulfone),

in the formula, Gly represents glycidyl group; R represents eachindependently, an alkyl group having 1 to 10 carbons, a cycloalkyl grouphaving 5 to 7 carbons, or a hydrocarbon group having 6 to 20 carbonatoms which contains a cycloalkyl group having 5 to 7 carbons; inrepresents each independently a numeral of 0 to 4; when i is 2 or more,R may be the same or different from each other; and n represents arepeating number of 1 to 10.

In addition, the present invention relates to (II) an insulatingmaterial for build-up method having a resin-containing layer formed bycuring the thermosetting resin composition described for above (I).

The present invention also relates to (III) a build-up print circuitboard formed by using the insulating material described for above (II).

DETAILED DESCRIPTION OF THE INVENTION

The thermosetting resin composition of the present invention is athermosetting resin composition for build-up method which contains(A) anepoxy resin represented by formula (I), (B) a curing agent for epoxyresin, and (C) a poly(ether sulfone).

In the present invention, the epoxy resins represented by the formula(1), can be used alone or in combination of two or more. In view ofcuring property, in the formula, it is preferable that R is methyl,ethyl, propyl (including isomers), butyl (including isomers).cyclopentyl or cyclohexyl; i is a numeral of 0 to 3, and n is arepeating number of 1 to 5. It is more preferable that R is methyl,ethyl, or t-butyl; i is a numeral of 0 to 2, and n is a repeating numberof 1 to 3.

The amount of the component (A) can be suitably selected in conjunctionwith other components and usually 1% by weight or more, preferably 1 to80% by weight, based on the total amount of (A), (B) and (C) of thecomposition.

Process for producing the component (A) can be adopted among knownprocesses including, for example, a process in which a phenol compoundor its derivative is reacted with an epihalohydrin in the presence of analkali such as sodium hydroxide.

In the present invention, known compounds can be used as the curingagent for epoxy resin as the component (B). Examples include polyhydricphenol curing agents for epoxy resin such as phenol novolac, cresolnovolac, phenol-modified polybutadiene and the like; amine curing agentsfor epoxy resin such as dicyandiamide, diaminodiphenyl methane,diaminodiphenyl sulfone and the like; acid-anhydride curing agents forepoxy resin such as pyromellitic acid anhydride, trimellitic acidanhydride, benzophenone tetracarboxylic acid dianhydride and the like;and so on. One or more of them can be used. Among them, polyhydricphenol curing agents for epoxy resin such as phenol novolac arepreferred from the viewpoint of low water absorption of cured product.

The amount of the component (B) may usually be determined so that thecured product obtained from the thermosetting resin composition of theinvention has a high glass transition temperature. For example, a phenolcuring agent is used as the component (B), the ratio of the epoxyequivalent of the component (A) and the hydroxyl group equivalent of thecomponent (B) is usually 1:0.8 to 1:1.2, and preferably 1:1. When anamine curing agent is used as the component (B), the ratio of the epoxyequivalent of the component (A) and the amine group equivalent of thecomponent (B) is usually 1:0.6 to 1:1, and preferably 1:0.8. When anacid anhydride curing agent is used as the component (B), the ratio ofthe epoxy equivalent of the component (A) and the carboxyl groupequivalent of the component (B) is usually 1:0.8 to 1:1.2, andpreferably 1:1.

The sum of the components (A) and (B) is usually 5 to 90% by weightbased on the total amount of the components (A) to (C) of thecomposition.

In the present invention, known compounds can be used as the poly(ethersulfone) as the component (C). A terminal group of the poly(ethersulfone) molecule includes, for example, a halogen atom, an alkoxygroup, a phenolic hydroxyl group and the like. From the viewpoint ofsolvent resistance and toughness of cured products, a phenolic hydroxylgroup is preferred. In this case, it is preferred that the bothterminals are phenolic hydroxyl groups. In the poly(ether sulfone)molecule, structural units other than the terminal(s) are notparticularly limited.

The amount of the component (C) is usually 10 to 70% by weight based onthe total amount of the thermosetting resin composition, and preferably10 to 50% by weight. When the amount is less than 10% by weight, thetoughness of cured products may decrease When the amount exceeds 70% byweight, processability of the composition may lower or the waterabsorption of cured products may increase.

Known process can be adopted as the processes for producing thecomponent (C). In addition, Examples of commercially available productsinclude Sumika Excel (trademark), manufactured by Sumitomo Chemical Co.,Ltd. and REDEL (trademark), manufactured by Amoco Chemicals Corp.

The thermosetting resin composition of the invention may contain (D) acuring catalyst, for the purpose of promoting cure reaction. Knowncompounds can be used as the component (D). Examples include organicphosphine compounds and triphenyl borane complex thereof such astriphenylphosphine, tri-4-methylphenylphosphine,tri-4-methoxyphenylphosphine, tributylphosphine, trioctylphosphine,tri-2-cyanoethylphosphine and the like; quaternary phosphonium saltssuch as tetraphenylphosphonium tetrafluoroborate, tetrabutylphosphoniumtetraphenylborate and the like; tertiary amines such as tributylamine,triethylamine, 1,8-diazabicyclo[5,4,0]undecene-7, triamylamine and thelike; quaternary ammonium salts such as benzyl trimethyl ammoniumchloride, benzyl trimethyl ammonium hydroxide, triethyl ammoniumtetraphenylborate and the like; imidazole compounds such as2-ethylimidazole, 2-ethyl-4-methylimidazole and the like; and so on. Oneor more of them can be used. Among them, organic phosphine compounds andimidazole compounds are preferred.

The amount of the component (D) can be suitably selected so that the geltime of the thermosetting resin composition of the invention is thedesired value. Usually, preferred gel time of the thermosetting resincomposition is 1 to 15 minutes at a temperature within a range of 80° C.to 250° C.

In addition, the thermosetting resin composition of the invention maycontain, if necessary, a thermosetting resin other than the component(A). Examples include epoxy resins other than the component (A), cyanateresins, addition polymerization products of bismaleimids and diamines,alkenyl aryl ethers such as bisvinyl benzyl ether compounds of bisphenolA and the like, alkenylamine resins such as vinylbenzyl compounds ofdiaminodiphenylmethane and the like, alkynyl ethers such as dipropargylether of bisphenol A and the like, alkynylamine resins such as propargylcompounds of diaminodiphenylmethane and the like, phenol resins, resolresins, allylether compounds, allylamine compounds, isocyanates,triallylisocyanurates, triallylcyanurates, vinyl group-containingpolyolefine compounds and so on.

As the epoxy resins except the component (A), exemplified are, forexample, di-functional epoxy resins derived from dihydric phenols suchas bisphenol A, bisphenol F, tetrabromobisphenol A, bisphenol S,dihydroxybiphenyl, dihydroxynaphthalene, dihydroxystilbene,alkyl-substituted hydroquinone and the like; novolac type epoxy resinderived from novolacs such as phenol novolac, cresol novolac, naphtolnovolac, bisphenol A novolac and the like; polyfunctional epoxy resinsderived from polycondensation products of phenol compounds such asphenol, alkyl-substituted phenol, naphthol and the like with divalentaldehydes such as terephthalaldehyde, alkyl-substitutedterephthalaldehyde and the like; epoxy resins derived from polyadditionproducts of phenol compounds with cyclopentadiene; and so on.

Further, the thermosetting resin composition of the invention maycontain, if necessary, a thermoplastic resin other than the component(C). Examples include polysulfones, polyetherimides, polyphenyleneethers, polystyrene, polyethylene, polybutadiene, polyimides,polycarbonates, polyacrylates, polymethacrylates, terminal amine- andterminal carboxyl-modified polybutadiene-acrylonitrile rubbers, modifiedcompounds thereof and the like.

Still, the thermosetting resin composition of the invention may beconferred with photosetting property, if necessary. For example,acrylates, methacrylates, styrene compounds or the like can becontained.

Still further, the thermosetting resin composition of the invention maycontain, if necessary, known additives including organic flame retardersuch as bromo-containing polycarbonates, bromo-containing polyphenyleneoxides, bromo-containing polyacrylates, bromo-containing polystyrenesand the like; inorganic flame retarder such as antimony trioxide,aluminum hydroxide, phosphorus red and the like; mold release agent suchas waxes, zinc stearate and the like; surface treatment agent such assilane coupling agent and the like; organic filler such as powdery epoxyresins, powdery melamine resins, powdery urea resins, powdery guanamineresins, powdery polyester resins and the like; inorganic filler such assilica, alumina, titanium oxide, and the like; and so on.

The thermosetting resin composition of the invention is suitably used asa raw material for a resin-containing layer of insulating material inthe build-up method, because the cured product obtainable therefrom isexcellent in heat resistance. In addition, other applications of thethermosetting resin composition of the invention may include insulatingmaterials for use in a method other than the build-up method, compositematerials, adhesive materials, painting materials and the like.

In the present invention, the insulating material for build-up methodrefers to a material having a resin-containing layer produced by curingthe thermosetting resin composition of the invention in the form of asheet or a film. The resin-containing layer may be piled. The thicknessof one resin-containing layer is usually within a range of 10 to 300μm.

Processes for producing the insulating material include, for example,processes (i) and (ii) described below:

(i) Components for use in the thermosetting resin composition of theinvention are mixed with a solvent such as γ-butyrolactone,dimethylformamide (DMF), N-methylpyrrolidone (NMP) or the like, ifnecessary. The mixture is directly applied on a core board with a rollcoater or a table coater. After evaporating the solvent, the mixture iscured by heating to form an insulating layer. Then a circuit is formedby laser process or plating process and this procedure is repeated toform a build-up layer (insulating layer).

(ii) Components for use in the thermosetting resin composition of theinvention are mixed with a solvent such as γ-butyrolactone,dimethylformamide (DMF), N-methylpyrrolidone (NMP) or the like, ifnecessary. The mixture is applied on a copper leaf using a table coateror the like to form a thin film. Then the film is treated by heat whileevaporating the solvent to form a semi-cured resin-copper leaf. The sameleaves are piled one by one onto a core board and cured by heating toform a circuit. This procedure is repeated to form a build-up layer(insulating layer).

In the process (i), conditions for evaporating the solvent are suitablyselected according to the components used in the thermosetting resincomposition and kind and amount of the solvent. Usually, the conditionsinclude a temperature within a range of 60° C. to 200° C. for 1 to 30minutes. The curing method by heating includes, for example, a methodconducted under conditions including a temperature within a range of 60°C. to 200° C. for 30 minutes to 5 hours in a hot gas oven.

On the other hand, in the process (ii), conditions for heating toperform semi-curing are suitably selected according to the componentsused in the thermosetting resin composition and kind and amount of thesolvent. Usually, the conditions include a temperature within a range of60° C. to 200° C. for 1 to 30 minutes. The curing method by heating ofthe resin-copper leaf includes, for example, a method of heat-pressingconducted under conditions including a temperature within a range of 80°C. to 250° C. for 20 to 300 minutes under a molding pressure of 10kg/cm² to 100 kg/cm².

The insulating material of the invention is suitably used as a rawmaterial for a build-up print circuit board, because it is excellent inheat resistance. The process for producing the build-up print circuitboard may be a known process. In addition, the insulating material ofthe invention can be used as a raw material for print circuit boardother than the build-up print circuit board.

EXAMPLES

The present invention will now be described by reference of Examples,which should not be construed as a limitation upon the scope of thepresent invention.

EXAMPLES 1, 2, 3 AND 4; COMPARATIVE EXAMPLES 1 AND 2

Components and solvents listed in Table 1 were mixed in a ratios (inparts by weight) described in Table 1. The. obtained mixtures werespread all over Teflon sheets to a thickness of about 200 μm. These weredried at 100° C. for 10 minutes under vacuum to form semi-curedproducts. The semi-cured products were heat-pressed at a pressure of 50kg/cm² and under conditions described in Table 1 to give cured products.The obtained cured products were assayed for glass transitiontemperature (Tg) by using a thermoanalysis apparatus TMA 120manufactured by Seiko Electronic Ind. The results are shown in Table 1.

TABLE 1 Compar- Compar- ative ative Exam- Exam- Exam- Exam- Exam- Exam-ple 1 ple 2 ple 3 ple 4 ple 1 ple 2 Epoxy — — — — 70 45.5 resin-1 Epoxy57 46.9 57 46.9 — — resin-2 Phenol 28 23.1 28 23.1 — 24.5 novolacPES5003P — — 15 30 — — PES4800P 15 30 — — 30 30 2E4MZ 0.1 0.1 0.1 0.1 50.1 DMF 100 100 100 100 100 100 Tg (TMA 216 220 205 204 176 150 method)Curing 175° 175° 175° 175°  80° C. × 175° condition C. × C. × C. × C. ×0.5 h C. × 2 h 2 h 2 h 2 h 120° C. × 2 h 2 h 150° C. × 4 h Epoxyresin-1: an epoxy resin derived from cresol novolac (manufactured bySumitomo Chemical Co., Ltd.) Epoxy resin-2: an epoxy resin derived frompolycondensate of 2-t-butyl-5-methylphenol and 4-hydroxybenzaldehyde(prepared according to JP-B-7-121979, Referential Example 1). Therepeating number n is about 1.5. Phenol novolac: manufactured by ArakawaChemical Industries, Ltd. PES5003P: poly(ether sulfone) (trademark:Sumika Excel 5003P of terminal phenolic hydroxyl group type,manufactured by Sumitomo Chemical Co., Ltd.) PES4800P: poly(ethersulfone) (trademark: Sumika Excel 4800P of terminal chlorine type,manufactured by Sumitomo Chemical Co., Ltd.) 2E4MZ:2-ethyl-4-methylimidazol

The thermosetting resin composition for build-up method according to thepresent invention gives a cured product excellent in heat resistance.Using said thermosetting resin composition, a useful insulating materialfor build-up method as well as a build-up print circuit board areprovided.

What is claimed is:
 1. An insulation layer having a thickness of 10 to300 μm used for build-up method, wherein the layer is formed by curing athermosetting resin composition comprising (A) an epoxy resinrepresented by formula (I), (B) a curing agent for epoxy resin, and (C)a poly(ether sulfone),

in the formula, Gly represents glycidyl group; R represents eachindependently, an alkyl group having 1 to 10 carbons, a cycloalkyl grouphaving 5 to 7 carbons, or a hydrocarbon group having 6 to 20 carbonatoms which contains a cycloalkyl group having 5 to 7 carbons; irepresents each independently a numeral of 0 to 4; when i is 2 or more,R may be the same or different from each other; and n represents arepeating number of 1 to
 10. 2. The insulation layer according to claim1, which the thermosetting resin composition further comprises (D) acuring catalyst.
 3. An insulating material for build-up method havingthe layer of claim 1 or
 2. 4. A build-up print circuit board formed byusing the insulating material of claim 3.